1. Field of the Invention
The present invention relates to a wet-type electrophotographic image forming apparatus. More particularly, the present invention relates to an oxidation catalyst device for making oxidation resolution of carrier vapors generated in a fixation device and a wet-type electrophotographic image forming apparatus having the oxidation catalyst device.
2. Description of the Related Art
In general, a wet-type electrophotographic image forming apparatus is a printing apparatus, in which a laser beam is scanned onto a photosensitive medium thereby forming an electrostatic latent image. A developer is then deposited on the electrostatic latent image, thereby forming a visible image, and the visible image is transferred to paper. As a result, a desired image can be printed out. The wet-type electrophotographic image forming apparatus is particularly useful for color printing, because it can produce a more distinct image as compared to a dry-type electrophotographic image forming apparatus which uses powder toner.
FIG. 1 is a schematic view of a conventional wet-type electrophotographic image forming apparatus. The conventional wet-type electrophotographic image forming apparatus 100 comprises an image forming apparatus body 110, a plurality of photosensitive drums 121, 122, 123 and 124, a plurality of charging devices 131, 132, 133 and 134, a plurality of exposure devices 141, 142, 143 and 144, a plurality of developing devices 151, 152, 153 and 154, a transfer belt 160, a plurality of first transfer rollers 171, 172, 173 and 174, a second transfer roller 180, and a fixation device 190.
The plurality of developing devices 151, 152, 153, 154 store developers of different colors, respectively, and each of the developing devices supplies a color developer to corresponding one of the plurality photosensitive drums 121, 122, 123 and 124. The developers typically consist of toner-dispersed ink and liquid carrier such as norpar. The norpar is a hydrocarbon-based solvent, which is a mixture of C10H22, C11H24, C12H26, and C13H28. The developers are deposited on the respective photosensitive drums 121, 122, 123 and 124, thereby forming visible images. The visible images formed on the respective photosensitive drums 121, 122, 123 and 124 are moved onto the transfer belt 160, and transferred onto a paper P by the transfer roller 180. The paper P that receives the transferred developers is moved into the fixation device 190. When the paper P passes through the fixation device 190, the ink of the developers is fixed onto the paper. The liquid carrier of the developers is vaporized in the form of a combustible hydrocarbon gas such as CH4 by a high temperature, and then discharged to the outside.
The combustible hydrocarbon gas is classified as a volatile organic compound (VOC), and can contaminate the local environment and emit an offensive odor when discharged as described. Accordingly, various methods for removing the combustible hydrocarbon gas have been developed in recent years.
Methods for removing the combustible hydrocarbon gases presently known in the art include a filtration method for physically removing gaseous components that uses a carbon filter such as active carbon. Other methods include a direct combustion method for combusting gaseous components at an ignition point (600° C.–800° C.), and a catalytic oxidation method for combusting gaseous components at a relatively lower temperature (150° C.–400° C.) that uses a catalyst by which the components are subjected to oxidation resolution and turned into water and carbon dioxide.
In the filtration method, however, the carbon filter does not have the capability of resolving the carrier vapors entrained therein. A carbon filter saturated with carrier vapors should be exchanged frequently with a new one when the carrier vapors are entrained over a predetermined amount in the carbon filter. The direct combustion method has the problem of potentially being unsafe.
Due to these problems, the catalytic oxidation method has been the preferred method in recent years. In addition, research has been conducted for realizing an oxidation catalyst device that has the benefits of good efficiency in oxidation resolution of carrier vapors, a high degree of stability in use and being safer than other methods.